Insulative materials are widely used in semiconductor fabrication methods for forming structures to electrically isolate the various active components formed in integrated circuits. Devices that extend into a semiconductive substrate can be electrically isolated by insulative materials formed within the substrate between the components, for example, trench isolation regions. In such a technique, trenches are etched into a silicon substrate, usually by anisotropic etching, and the trenches are subsequently filled by the deposition of an oxide such as silicon dioxide (SiO2).
Due to the reduction in component size, microelectronic devices now require processing methods for forming nanosized components and accompanying silicon dioxide films. Such films have been achieved using atomic layer deposition (ALD) to control the growth of the film.
ALD processes proceed by chemisorption of a monolayer of reactive precursor molecules at the surface of the substrate. A series of reactive precursors are then alternately pulsed into a deposition chamber, separated by an inert gas purge. Each pulse of a precursor results in a new atomic layer over the previously deposited layers. The cycle is repeated until a desired film thickness is achieved.
However, the rate of deposition of silicon dioxide to fill a trench or other opening using an ALD process is less than desirable.